1. Field of the Invention
The present invention relates to an active remote sensing system. More particularly, the present invention identifies chemical and/or biological materials (CBMs) at a distance by interrogating the materials with infrared laser light. Most particularly, the device and method of the present invention interrogate CBMs with modulated polarized infrared laser light, collect backscattered polarized infrared laser radiation, electronically record the information from the collected polarized infrared radiation, and mathematically analyze the information to identify the CBMs. Additionally, the device and method may determine the distance to the CBMs.
2. Brief Description of the Related Art
Distant detection and classification of chemical and/or biological materials (CBMs) or contaminates is desirable, especially for military operations. Long range detection and classification eliminate health hazards and coordination problems on a battlefield. Once the presence of a particular CBM is known at a location, preventive measures may be taken prior to entering the area.
Mueller matrices are mathematical calculations and representations of irradiated materials. U.S. Pat. Nos. 4,306,809 (Azzam), 4,953,980 (DeVolk et al.), 4,884,886 (Salzman et al.), 5,247,176 (Goldstein), 5,631,469 (Carrieri et al.), 5,659,391 (Carrieri), and 5,708,503 (Carrieri) disclose many aspects of passive and active systems which process and transform scattergrams into Mueller elements.
Those skilled in the practice of nepholometry and photopolarimery typically use back-inversion methods that correlate the Mueller elements to the geometry and/or physical properties of the interrogated compound or scatterer. The Mueller matrix instrument has a linear polarizer and a modulated PEM positioned in the transmitted beam, and a plurality of modulated PEM's and another linear polarizer positioned in the received beam. This combination of optical elements is referred to as a Mueller matrix spectrometer, MMS.
In view of the foregoing, improvements in CBM identification have been desired. There is a need for selective CBM identification and improved efficiency of using Mueller matrix elements in CBM identification. Additionally, it has been desired to provide the location of the identified CBMs.